The invention relates to a method and a machine for the mechanical embellishment, including fine perforation, of precoined metal strip, working from continuous stock or from discrete lengths.
Prior art methods of manufacturing precious metal and costume jewelry embrace machines which are capable of turning out items in a variety of shapes, with a specular embellishment obtained by machining. Certain of these machines, on which rights are also claimed by the same applicant, produce the specular machined embellishment on rolled materials tensioned longitudinally over rotary supports.
In other types of machines, on which rights are similarly claimed by the same applicant, items exhibiting a specular embellishment produced by synchronized mechanical cutting are obtained from a strip of geometrically defined width, gripped either side, which, following embellishment, are coined and then embellished further over the coined areas. The items are then separated by shearing through the strip in readiness for further finishing operations.
Those machines employed, in particular, for the specular embellishment and subsequent coining of items piece by piece, include a support that will grip and tension the previously formed material, the surface of which can then be machined at a series of rotary tool stations.
It is common practice when using such machinery to employ a packing, located between the support and the sheared and formed piece of material, which serves a dual purpose of affording a cushion to the coined imprints, and avoiding contact between the tools and the support. The use of packing material is of great importance, not only in protecting those parts of the support embodied in relief, but also in assisting embellishment, generally implemented with rotary tools. Its effect is to permit a cleaner, more specular machining, while preventing the strip material from vibrating at the point where the tool cuts into the coined imprint.
The packing providing support and protection in this way must necessarily be replaced each time the work is changed, in order to prevent a tool from penetrating the hollow of an imprint and thus damage the work as a result of its being subjected to jerking and vibration from the tool itself.
With such a requirement in mind, packing is currently fashioned in a plastic or paper material and pre-compressed in a mold. Though the costs are high, especially when one considers that in order to perform the function in question, the shape must be altered in each instance to match the profile of the work.
Aside from the drawback of cost, the use of packing as referred to is also beset by a practical disadvantage, inasmuch as a given strip may exhibit a number of dissimilar coined imprints, or differing layout of such imprints, along its length, in which case the packing must exhibit the same pattern.
The object of the invention is to eliminate the drawbacks aforementioned.